This invention relates to a diathermy unit.
Conventional mains-powered diathermy units commonly apply radio frequency (r.f.) energy to the tissue to be treated at a power level determined by a power control circuit for controlling the amplitude of the r.f. signal generated by an r.f. oscillator. However, in practice, human tissue presents a widely variable electrical load, resulting in poor impedance matching of the r.f. output of the unit to the load in most circumstances so that, of the power generated, often only 20 per cent is dissipated in the load. Bipolar diathermy typically requires an applied r.f. power level of 10 watts, but in view of the inefficiency resulting from poor matching, a unit capable of generating much higher power levels than 10 watts is necessary, and for this reason a diathermy unit designed for hand held use would be large and unwieldy, especially if battery-powered.